Amd william



H. H. DOW AND W. 0. QUAYLE. METHOD OF MANUFACTURING CHLOROFORM. APPLICATION FILED JUNE 8. 1914.

1,8 1 1,329,. Patented July 29, 1919.

. a rares TON, DELAWARE, ASSIG NORS TC THE MICHIGAN, A CQRPO'BATION 015 MICHIGAN.

' nnnnnrer n. new, or MID AND, MICHIGAN, AND wrnmnin o. con-ran, or wrnrrrn'enow cnnrrrcnn comma, or rnrntnnn METHOD OF MANUFACTURING CHLOEOFQRM.

reins-2a.

Specification of Letters Patent. Patented July 29., 1911.9.

Application filed June 8, 1914 Serial No. 843,605.

To all whom it may concern:

Be it known that HERBERT zen of the United States, residing at Midland, in the county of Midland and State of Michigan, and WILLIAM G. QwAYLE- Q a citizen of the United States, residing at -Wilmington, in the county of New. Castle and State of Delaware, have invented a cer- 'tain new and usefullm rovement in Methmaking taking place was that indicated by lowing formula: 2CCl +2H O+2Fe:

ods of Manufacturing (L oroform, .of which the following is a full, clear, and exact description, reference being had to the accompanying drawing.

- This invention relates to the manufacture :finally the reduction of the carbon tetrachlorid to chloroform. The last of these reactions, which is the, one with which this application is concerned, was efi'ected' by agitation of the liquid with finely divided;

metallic iron in a suitable container-or reaction vessel, suitable expedients' being, provided whereby the temperature of the mass could be controlled. The principal reaction the fol- The temperature during this reaction must,

however, be carefully controlled, since, it a1 lowed to rise, the'ohlorotonn is also reduced according to the following reaction:-

and at such higher temperatures, other do composition products of carbon tetrachlori'd are formed in greater proportions.

l For this reason, Dr. Smith in the afore- Jsaid Letters Patent suggested adding the iron in successive small portions, so that no u. Dow, a citi-' in a double walled vessel provided with means for circulating water or other cooling fluid between the two portions of the shell, a temperature of about 15 (3: being employed. 4

Experience has shown that if the temperature of the container and contents be maintained at any point below, say, 20- (1, a very satisfactory yield is obtained, with only a very small loss in the-form of dichlormethane. However at this low temperature the reduction isfso extremely slow as hardly to be a commercially feasible process; if the temperature is increased so as to quicken the action a lower yield is olotainedging-to the overreduction of a larger percentage of the charge. Also, as the proportion of chloroform in the container was increased the opportunity for over-reduction became multiplied, thus rendering it impraoticable to continue the operation longer than necessary to reduce about fifty per cent. of the tetra ch'lorid. When this point was reached the temperature would be raised and-the chloroform together with the unreduced tetrachlorid removed from the iron and hydrated I ferric oxtid by distillation. However this distillation occupied considerable time and necessitated temperatures considerably above those of most efiicient reactions, so that during this process of distillation both the chloroform and the tetrachlorid underwent serious destructive reduction which-- not only decreased the yield of chloroform hut'mixed that chloroform with undesirable destruction products which had to he freed therefrom by a slowand expensive "process of separation. I

' Our experiments .have shown-that if the vapor pressure within the reaction vessel be reduced to that at which the mixture of caricon tetrachlorid and chloroform resulting from the reaction will boil, and the vapors so produced, (oonsistin chiefly of'carbon tetrachlorid and ohloro brm together with some water), be fractio nally condensed and the* carbon tetrachlorid and water he re turned to the reacting mixture, important advantages may be. realized. Working in this manner, the percentage of chloroform! in the reacting mixture is kept at a'.minimum, beingremoved therefrom substantiallyment owing as fast as formed. The reduction is therefore confined chiefly to the predominating carbon tetrachlorid and very little overreduction takes place, hence a better yleld is obtained. Also it is possible to employ higher temperatures and hence increase the rapidity of the that the chloroform is removed so soon after formation as to minimize its opportunity for further reduction. Moreover, under reduced pressure as above described, the process may be continued until substantially all of the charge of tetrachlorid has been reduced, necessitating less of it in process and, in addition, producing a chloroform which is more nearly free from undesirable products and .can be m-0re\cheaply purified and finished. Further, the reaction vessel is more constantly producing chloroform and that under unifonncondritlons, insuring best yield and purity of product. Finally, it is possible to add all the iron or other reducing agentrequired for the operation at one time, such amount in the case of iron, being always in excess of the theoretical requireto the difiiculty of obtaining complete oxidation.

In the drawings accompanying and forming a part of this specification we have illustrated one form of apparatus with which our improved process may be carried out,

although it will be understood that the same is only one of many'forms which could be employed within the scope of our invention. Describing the parts by reference characters,

- 1 represents the reaction vessel which preferably consists of a substantially cylindrical metal drum having an outer wall 2 spaced therefrom at all points to form a fluid jacket, the whole being rotatably journaled in suitable standards 3-3 by means of trunnions 4: and 5. The trunnion 4 is provided with a pair of concentric pipes 6 and 7, respectively, communicating with this fluid jacket, these pipes being connected by means of the swivel joint 8 with waste and supply pipes 9 and -10. The trunnion 5 is provi ed with the central pipe 11 communicating with theinterior of the receptacle 1 and connected by means of the swivel joint 12 with an inclined conduit 13, the opposite end of which is attached to the lowermost chamber 14 of a fractionating column 15. Connected I to umn through the dephlegmator 16 is a suitable vacuum pump 17 the exhaust from the pump passing into the final condenser 18, which in turn discharges into the receiver 19. The side of the reaction vessel is preferably-provided with a removable cover 20 whereby the ingredients (carbon tetrachld rid, iron, and water) may be added, and the sludge remaining after the completion of the, reduction may be withdrawn. One of the trunnions, as 5, may also be provided reaction owing to the factfractionating col- Wlll with a gear wheel 21 or the like, whereby the cylinder is rotated and its contents thoroughly mixed.

In the performance of our lmproved process the receptacle 1 is charged witha mixture of carbon tetrachlorid, iron filings, borings, or dust and Water, the cover 20 is clamped securely in position, and a slow rotation of the receptacle commenced by means of the gear 21. At the same time the pump 17 is operated to reduce the pres final condenser 18, which drains into the 1 storage receptacle 19. The chloroform and carbon tetrachlorid, being of considerably the same chemical composition and not differing very greatly in volatility, pass into vapor together, and the pressure within the reacting-vessel is preferably so chosen that ebullition of the entire contents takes place with considerable freedom under the conditions of temperature maintained for the purpose. The vapors produced by this ebullition therefore consist of a mixture of chloroform and carbon tetrachlorid together with some water, but these possess difl'erent condensing points, condensin more easily than the chloroform and there ore being dropped in. the fractionating column andreturned to the receptacle by way of the-conduit 13. The surviving chloroform vapor is further cooled in the refrigerator 16 and is completely precipitated in the final condenser 18 under a pres sure approximately that of the atmosphere.

By removing the successive increments of chloroform from further contact with the reducing reagent soon after formation of the same, this process makes it practicable the carbon tetrachlorid to Work the reaction at, a somewhat higher 1 temperature than at present practised, thereby lncreasing an output ofthe apparatus and at the same time avoiding the losses which are involved by the methodheretofore'followed, due, to the holding of the chloroform in contact with the reducing reagent for a considerable time after its formation, especially at higlf temperatures. We have found by actual experience that a temperature of approximately 30 to 35 C. cause an ev lution of chloroform at a rate that makes it commercially feasible to manufacture this material, and that the purity of the product formed through this reaction is such as to make it the basis of a commercial process. Accordingly, the

retrace pressurewithin the apparatus being brought .to the necessary point, the temperature with- .point determined by this pressure, whereupon ebullition of the whole mass will take place the chloroform being volatilized substant1ally as rapidly as it is formed and passing directly to the fractionating column. Owing to the close chemical similarity of the substances, their rather similar boiling points even'under atmospheric pressure, and the fact that they are miscible together in all proportions, both chloroform and carbon tetrachlorid will be present in the vapors at all times, their relative amounts de pending upon the composition of the boiling mixture. Toward the end of the run when, eitherlby reason of the nearly complete oxidation of the iron or the nearly complete reduction of the carbon tetrachlorid, the output of the reaction vessel falls ofi, the temperature'may be raised (or the temperature and premure both, since there is no longer any danger of overreduction) and the carbon tetrachlorid remaining in thereaction vessel distilled ofi ,through the,

column 15 and'cau-ght separately by with.-

draw'al through the pipe 23 into the vessel gl'shall be less than atmospheric. -40

24,- after which the reaction vessel may be opened and the remaining waste product, consisting of a Water solution of ferrous chlorid mixed with ferric oxid and usually some 'unoxidized iron, may be dumped out and ;sthe vessel recharged for another run.

It will be understood that we do not limit ourselves to any'specific temperatures or pressures, except that the pressures used While we have suggested temperaturesof 30 to 35 C. herein, this is merely an indication of what we consider preferable and is not a limitation. It will also be understood that the present drawings are largely diagrammatic, that the fraction-sting column, refriger-ators, pumps, reservoir, etc, are shown in conventionalized form, that a great many changes in the construction of these elements and of their mode of connection and arrangement can be employed without departing from the scope of our invention.

shown, the same could 'be connected in other parts of the system,

While -we have described our invention in detail wed-o not therefore propose to be limited to such details except as the same may be positively included inthe claims hereto annexed or maybe rendered necessary by the prior state of the art.

.point that distillation will proceed concur:

' the reacting mixture.

'stanti-ally complete reaction, reducing the pressure and concurrently elevating the temperature in the reaction vessel to such a rently with the reaction, and-separating the chloroform'from the vapors so produced.

2. Tn a method of making chloroform, in which carbon tetrachlorid, water and a metal are caused to react, the steps which consist in maintaining the temperature of the reacting mixture at approximately 30 (3., reducing-the pressure over the reactin mixture to a pointat which distillation will proceed concurrently with the reaction, recovering separately the unreduced carbon tetrachlorid and chloroform from the vapors so produced, andreturning the unreduced carbon tetrachlorid so recovered to 3. Tn a method of making chloroform, in which carbon tetrachlorid, Water and a reducing agent are caused to react, the steps which consist in reducing the pressure over the reacting mixture and elevating the temperature of the same to a point at which distillation and reduction will proceedconcurrently at the desired speed, recovering separately the Junreduced carbon tetrachlori-d and chloroform from the, vapors so produced and returning the unreduced carbon tetrachlorid so recoveredto the reacting mixture.

4:. The method of manufacturing chloroform which consists in agitating water, carbon tetrachlorid, and finely divided metallic iron together in a suitable receptacle, main.-

.taining the temperature of the receptacle anditsc'ontents at a point between about 30 and 35 (3., maintaining the pressure lie within the receptacle at such a point that free ebullition of its contents will take place at such temperature, and condensing the chloroform separately from the vapors producedt 5. The method of manufacturing chloroform, which consists'in agitating togetherf,

water, carbon tetrachlorid, and finely dlq;

.vided metallic iron in a closed receptaclaf' such iron being in an amount in excess of that required for the actual reaction, maintaining the temperature of the receptacle and its contents between about 30 and 35 (1., maintaining the pressure within the rece tacle' at a point where free ebullition of 1215 semi contents takes place at such temperature, and separating the chloroform from the vapors of such ebullition.

6. The process or making chloroform which consists in reacting on carbon tetra 13c chlorid with water and finely divided metallic iron in a reaction vessel m'antained under reduced pressure, withdrawing co incidentally with the progress of the reaction, the vapors formed over the reacting mixture, fractionating such vapors under re, duced pressure, returning the condensed and separated carbon tetrachlorid to the reaction vessel, and finally condensing and diverting into a separate vessel the chloroform in the surviving va ors whereby the chloroform produced an volatilized is removed from further contact with the reducing agent.

7. In a method of making chloroform in which metallic iron is caused to react upon carbon tetrachlorid in the presence of water, the steps which consist in maintaining the temperature of the reacting mixture substantially between about. and 369 (3.,

I maintaining the vapor pressure at such tetrachlorid by means point that distillation will occur at that temperature, and separating the chloroform from the vapors evolved. v

-8. The method of manufacturing chloroform which consists in reducing carbon of finely divided me- .tallic iron in the presence of water, in a closed vessel at a temperature which will cause the production of commercially pure chloroform,

to boil at that particular temperature, and subjecting the vapors to fractional condensation whereby the chloroform is separated and recovered from the unreduced carbon tetrachlorid.

9. In a method of making chloroform in which metallic iron is caused to react upon carbon tetrachlorid in the presence of water,

the steps which consist in mamtaining the temperature of the reacting mixture substantially between 30 C. and 35 C maintainand under a pressure which ing the vapor pressure inv the reactin vessel at such point that distillation wil proceed concurrently with the reaction,'recovering separately the unreduced carbon tetrachlorid and chloroform from the vapors so roduced, and returning the condensed caron tetrachlorid to the reacting mixture.

10. In a method of making chloroform in Which metallic iron is caused to react upon carbon tetrachlorid in the presence of water, the steps which consist in maintaining the temperature of the reacting mixture substantially between 30 taining the vapor pressure in the reacting vessel substantially at the boiling point of chloroform for the temperature employed, removing the evolved vapors from the reacting vessels substantially as rapidly as formed, condensing them separately, and returning the condensed carbon tetrachlorid to the reacting mixtur i 11; In the method of making chloroform in which a reducing agent is caused toreact upon carbon tetrachlorid in the presence of water, the regulating step which consists in maintaining the vapor pressure within the reaction vessel at that point which corresponds to the boiling point of chloroform atlthe reaction temperature desired.

0. and 35 C., main In testimony whereof, we hereunto afix our signatures in the presence oftwo wit-' nesses.

HERBERT I-I. DOW.

. WILLIAM O. QUAYLE.

Witnesses to signature of Herbert H.

Dow:

Tnos. GRIswoLD, Jr., M. F. ANDERSON.

Witnesses to Quayle:

P. E. Srmomnn,

'R. H. RAWLEIGH.

signature of William O. 

